(CNN) -- President Obama has directed U.S. intelligence, law and Homeland Security agencies to take steps to ensure American safety and determine whether the suspicious package threat is part of terrorist plotting.

The president was notified of the potential terrorist threat at 10:35 p.m. ET on Thursday by John Brennan, his assistant for homeland security and counterterrorism, White House Press Secretary Robert Gibbs said in a statement.

"The president has received regular updates from his national security team since he was alerted to the threat," Gibbs said.

On Thursday night, intelligence and law enforcement agencies discovered potential suspicious packages on two planes in transit to the United States, Gibbs said.

"Based on close cooperation among U.S. government agencies and with our foreign allies and partners, authorities were able to identify and examine two suspicious packages, one in East Midlands, United Kingdom, and one in Dubai. Both of these packages originated from Yemen," Gibbs said.

Additional security measures were deployed for flights at Newark Liberty and Philadelphia International Airports, Gibbs said.